This invention relates to a bladder type solar energy collector device. More particularly, this invention relates to a bladder type solar energy collector device which is resistant to deterioration by ultraviolet rays and which maximizes heat retention by means of enclosing the bladder in a heat absorbing insulated housing.
Various types of solar collectors for the heating of water have been developed and marketed in the recent past. Some operate with the continuous circulation of water through loops and coils and some are batch type, heating a reservoir of water. It is to the batch type of collector that the present invention is drawn.
U.S. Pat. No. 3,029,806 and 3,052,228 to Okuda show a bladder type of solar collector made of bonded pieces of flexible plastic wherein the top sheet is transparent to allow the transmittance of radiant energy and the bottom sheet is black to absorb radiant energy. U.S. Pat. No. 3,052,228 also provides a means for entering the bladder to clean slime and algae from the interior thereof.
While this type of collector will indeed provide heated water, it also has considerable drawbacks. Algae, slime or other impurities formed in the bladder are transported from the collector when the heated water is withdrawn. These impurities make it unattractive to utilize water thus heated for culinary or bathing purposes. Also, plastics and dark pigmented plastics in particular, are susceptible to deterioration caused by prolonged exposure to ultraviolet rays of light. This is particularly so when the solar bladder is empty and the ultraviolet rays are absorbed by the plastic skin of the bladder. The result of repeated exposure, particularly of black pigmented plastics, to ultraviolet rays is brittleness and cracking.
Even though the above drawbacks pertain to bladder type solar collectors, there are considerable advantages which are also applicable to this type of collector. A pump is not required to constantly circulate water. The collector can be left unattended over prolonged periods of time. A predetermined amount of water can be placed in the collector bladder and the bladder can be drained on an as needed basis, or when a predetermined water temperature has been reached. Maintenance problems are minimal in that complicated valves, monitoring and pumping equipment are not required.
Other patents utilizing flexibile plastic type of solar collectors are taught in U.S. Pat. Nos. 3,022,781; 3,513,828 and 4,520,793.
It may therefore be seen that if the problems associated with unwanted impurities and deterioration of the bladder skin were to be solved, that these types of collectors present many advantages, particularly in circumstances where batch types of water heating are useful.